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MG MGB Technical - OD not spinning

Well after years of saying I would, I finally picked up an LH style O/D transmission for my 69 BGT. It is allegedly in good working order but I plan on testing it and doing gaskets etc.. prior to install.

But right now the out put flange, coming directly out of the over drive unit does not spin freely. A local MG shop told me this was normal and that it would free up easily. So did I just by a boat anchor, or is this relatively common?

-Bill
Bill Mertz

Hi Bill,
I have my gearbox with LH o/d attached on the garage floor at the moment. Just tried to spin the output shaft and it's very free. Can't explain what you've got but it may just be stuck from standing still for years. Mine's only been out of the car for 18 months!!
A strip down costs little so dive in.
Richard
Richard Coombs

Bill,

if you have a look at your workshop manual, you will find out that the hydraulic pump of the OD is engaged all the time. So you can not compare the load for spinning the tail shaft of an OD gear box with a four speed version.

Before installing the OD gear box, just check if the solenoid is working and if the sump and the sump gasked (with it's incorporated filter screen) of the OD are clean.

If your gearbox is a side fill version, top it up with 20W50 as described in the manual before you drop it into your car.

Ralph
Ralph

After sitting for seven years mine turned easly but would not spin freely.
John H

I would definitely take the overdrive apart and check it, I am installing on OD in my 79, it was working fine but I thought I would check it anyway, the image below is what I found.



The Wiz

i have never seen this before. O.K., mangeled gears appear sometimes, but it would be interesting to know whether the locking pin came apart (or was not installed at all) or if there was a faulty repair done some time before you investigated this.
Any further suppositions?

Ralph
Ralph

Ralph, the car I took the overdrive from had been very badly treated by its previous owner, the gearbox was dry when I got the car. I really think it was lack of oil, this wasn't the only problem with the gearbox.

The Wiz

Yikes!
Maybe I will have a peak at it.
Bill Mertz

The most common cause of planet gear assy failure is bacause who-ever took it apart last time didn't 'time the gears' They have mark on them & it should be in the same place on all gears when it is inserted in the annulus. I also fit V8 springs - 37H1928 (from O/D Spares) when-ever I have an O/D apart.
Garth
Garth Bagnall

Hi Bill- Of the dozen or so MGB OD I've been up close and personal with, the solonoid or blocked filter screen was the problem. Once, a pressure adjust was done, but that one slipped in and out: sorta half worked. I use a bench tester, a 1/2 inch Hole Hawg, right angle plumber's drill, chucked to an insert clamped to a piece of heater hose inserted over the input shaft and clamped ( maybe now any 1/2 inch slower speed drill off the shelf at HD will work). Works great to check the function of solonoid/ball bearing when 12 volts is applied. Clockwise rotation please. Good luck, VEM
vem myers

This thread was discussed between 16/06/2008 and 25/06/2008

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